.\"	$OpenBSD: ASN1_STRING_length.3,v 1.5 2016/11/10 11:44:52 schwarze Exp $
.\"	OpenSSL 99d63d46 Tue Jun 21 07:03:34 2016 -0400
.\"
.\" This file was written by Dr. Stephen Henson.
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.Dd $Mdocdate: November 10 2016 $
.Dt ASN1_STRING_LENGTH 3
.Os
.Sh NAME
.Nm ASN1_STRING_cmp ,
.Nm ASN1_STRING_data ,
.Nm ASN1_STRING_dup ,
.Nm ASN1_STRING_length ,
.Nm ASN1_STRING_length_set ,
.Nm ASN1_STRING_set ,
.Nm ASN1_STRING_to_UTF8 ,
.Nm ASN1_STRING_type
.Nd ASN1_STRING utility functions
.Sh SYNOPSIS
.In openssl/asn1.h
.Ft int
.Fo ASN1_STRING_cmp
.Fa "ASN1_STRING *a"
.Fa "ASN1_STRING *b"
.Fc
.Ft unsigned char *
.Fo ASN1_STRING_data
.Fa "ASN1_STRING *x"
.Fc
.Ft ASN1_STRING *
.Fo ASN1_STRING_dup
.Fa "ASN1_STRING *a"
.Fc
.Ft int
.Fo ASN1_STRING_length
.Fa "ASN1_STRING *x"
.Fc
.Ft void
.Fo ASN1_STRING_length_set
.Fa "ASN1_STRING *x"
.Fa "int len"
.Fc
.Ft int
.Fo ASN1_STRING_set
.Fa "ASN1_STRING *str"
.Fa "const void *data"
.Fa "int len"
.Fc
.Ft int
.Fo ASN1_STRING_to_UTF8
.Fa "unsigned char **out"
.Fa "ASN1_STRING *in"
.Fc
.Ft int
.Fo ASN1_STRING_type
.Fa "ASN1_STRING *x"
.Fc
.Sh DESCRIPTION
These functions manipulate
.Vt ASN1_STRING
structures.
.Pp
.Fn ASN1_STRING_cmp
compares
.Fa a
and
.Fa b
and returns 0 if the two are identical.
The string types and the content are compared.
.Pp
.Fn ASN1_STRING_data
returns an internal pointer to the data of
.Fa x .
Since this is an internal pointer, it should
.Em not
be freed or modified in any way.
.Pp
.Fn ASN1_STRING_dup
returns a copy of the structure
.Fa a .
.Pp
.Fn ASN1_STRING_length
returns the length of the content of
.Fa x .
.Pp
.Fn ASN1_STRING_length_set
sets the length attribute of
.Fa x
to
.Fa len .
It may put
.Fa x
into an inconsistent internal state.
.Pp
.Fn ASN1_STRING_set
sets the data of the string
.Fa str
to the buffer
.Fa data
of length
.Fa len .
The supplied data is copied.
If
.Fa len
is -1 then the length is determined by
.Fn strlen data .
.Pp
.Fn ASN1_STRING_to_UTF8
converts the string
.Fa in
to UTF8 format.
The converted data is copied into a newly allocated buffer
.Fa out .
The length of
.Fa out
is returned or a negative error code.
The buffer
.Fa out
should be freed using
.Xr free 3 .
.Pp
.Fn ASN1_STRING_type
returns the type of
.Fa x ,
using standard constants such as
.Dv V_ASN1_OCTET_STRING .
.Pp
Almost all ASN.1 types in OpenSSL are represented as
.Vt ASN1_STRING
structures.
Other types such as
.Vt ASN1_OCTET_STRING
are simply typedefed to
.Vt ASN1_STRING
and the functions call the
.Vt ASN1_STRING
equivalents.
.Vt ASN1_STRING
is also used for some CHOICE types which consist entirely of primitive
string types such as
.Vt DirectoryString
and
.Vt Time .
.Pp
These functions should
.Em not
be used to examine or modify
.Vt ASN1_INTEGER
or
.Vt ASN1_ENUMERATED
types: the relevant INTEGER or ENUMERATED utility functions should
be used instead.
.Pp
In general it cannot be assumed that the data returned by
.Fn ASN1_STRING_data
is NUL terminated, and it may contain embedded NUL characters.
The actual format of the data will depend on the actual string type itself:
for example for an
.Vt IA5String
the data will be ASCII, for a
.Vt BMPString
two bytes per character in big endian format, and a
.Vt UTF8String
will be in UTF8 format.
.Pp
Similar care should be take to ensure the data is in the correct format
when calling
.Fn ASN1_STRING_set .
.Sh SEE ALSO
.Xr ERR_get_error 3
